The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Diesel engines typically have higher efficiency than gasoline engines due to an increased compression ratio and a higher energy density of diesel fuel. A diesel combustion cycle produces particulates that are typically filtered from diesel exhaust gas by a particulate filter (PF) that is disposed in the exhaust stream. Over time, the PF becomes full and the trapped diesel particulates must be removed. During regeneration, the diesel particulates are burned within the PF. As emission standards increase, it is anticipated that particulate filters may be used in non-diesel applications as well.
Conventional methods initiate regeneration based on distance driven, time since last regeneration, fuel burnt, or predicted soot accumulation. Newer methods evaluate a pressure drop in the particulate filter to initiate regeneration. These methods use one or more predetermined tables to predict a pressure drop. The pressure entries in the predetermined tables are typically determined from nominal parts. Therefore, variations in the substrate of the particulate filters, variations in sensor properties, and various affects due to ash accumulation are not accounted for in the tables. This results in reduced accuracy in the prediction of soot in the filter.
For example, when there is a low limit part, the methods under predict the soot loading on the filter resulting in risk to the hardware during regeneration. When there is a high limit part, the methods over predict the soot loading on the filter resulting in too frequent regenerations which impacts fuel economy. The conventional methods also do not take into account variability of the accumulation based on drive cycle characteristics. Thus, the method has proven to be unreliable.